Alfawise 256GB, a brief review of a microSD card

Almost a year has passed since I published my review of the 128 GB card, and to my surprise I noticed that its price ($44.59) back then was almost the same as what the 256 GB card costs now: $44.99 ($41.99 with a coupon). So progress is being made, little by little. I hope the price drops further.
I’d also like to say that the 32, 64, and 128 GB cards are all still working perfectly.


So, the packaging looks very much like the previous one: the same triangular blister pack, with only the capacity, card standard, and read speed—up to 80 MB/s—listed as useful information.


The card itself comes in a small plastic “pocket.” What’s missing is an SD-to-microSD adapter, which would come in handy sometimes.


Last time, the card had a shark printed on it (the Mixza card); this time it’s a clearly Japanese-looking cat holding a fish in its paws :)
There’s no information about the card standard or its original manufacturer. The bottom only has generic markings showing the capacity and country of manufacture.


Someone once asked me to check who made the card. Back then, the program didn’t show anything. This time it says Samsung, although the SDU1 model points to Transcend. The phone also identifies it as Samsung.


For the test, I’ll use the fairly well-known and decent Transcend RDF5 card reader.


The card was formatted as exFAT, with a formatted capacity of 238 GB (256,000,000,000 / 1024/1024/1024 = 238.4).


In this case, the capacity test is more of a tradition, since I had no doubt that this really is a 256 GB card.
Write speed was around 48 MB/s, and read speed was 72 MB/s. Both remained stable.


The card also got very hot, though: during writing it reached 87–90 degrees, and during reading around 75–77. The card reader got very hot too, so it’s hard to tell which was heating up the other more. I wouldn’t recommend using cards under these conditions.


The most common speed test is CrystalDiskMark. I ran it in four configurations: two software versions and two connection types—USB 2.0 and 3.0.
Judging by the test results, the claimed read speed of 80 MB/s is accurate. The Mixza 128, however, was faster at writing, reaching 75–77 MB/s.


Rather than send you back to the previous review for the details, I’ll repeat the information about speed specifications here.
The packaging said SD XC, without even specifying a speed class, while the store page lists UHS-3 XC.
Flash card speeds are usually specified in terms of write speed, not read speed. The speed classes correspond as follows:


I’ll also quote some additional information from that review.


Judging by the previous test results, the card provides sequential write speeds of at least 45 MB/s, bringing it close to UHS-50.



Next are some additional tests. To keep them out of the way, I’ll put them under a spoiler.


I could have wrapped up the review on this relatively positive note, if it weren't for something odd in the last test: copying large files using Windows Explorer.
First, I picked a convenient 53 GB file—a virtual machine image that I also used for testing last time.
But the write test showed a rather low speed and, worse, speed drops. Under Windows 7, it simply looked like the process was slowing down. Read speed, on the other hand, was excellent.
I tried the same test on another computer running Windows 10. First, I simply copied the file from the card to the computer's SSD. Everything was fine: speed was over 80 MB/s, and the read graph was flat.
Next, I wiped the flash drive, rebooted the computer, and started writing the same file. I immediately noticed periodic drops in speed to zero—the so-called "freezes"—and about 20 minutes later, I got an error message. I used the same file, card reader, and computer, but connected to USB 2.0. It copied without any problems or freezes; average speed was around 28 MB/s, fluctuating between 22 and 35 MB/s.


This odd behavior caught my interest, and I ended up spending more time experimenting with it than on all the previous tests combined. But I found that writing a different file, around 7 GB and of a different type, caused no problems or freezes at all.
Under Windows 7, write speed looked stable; under Windows 10, it became "wave-like", but again, with no drops to zero or anything like that.
Both tests used a USB 3.0 connection. I could blame the file size, of course, but with the larger file, the drops started right from the beginning.


That's about it. I tried to keep this as short as I could. It's hard to draw any firm conclusions: on the one hand, the card works, its capacity is as advertised, and its speed is pretty good. But the strange behavior when copying a particular file surprised me a bit; perhaps someone can explain it. Also, the card gets noticeably hot during continuous sequential writing, which is worth keeping in mind. It would be interesting to repeat the tests with a card that hasn't been run so hard.

That's all from me. I hope you found the review useful. The store provided the coupon ALF256Xmas, which brings the price down to $41.99.